---
id: 65579228c669fcbebffd01d5
title: Passo 47
challengeType: 20
dashedName: step-47
---

# --description--

The other bug is subtle. When a shorter distance is found for a neighbor node, `paths[current]` gets assigned to the neighbor node path, `paths[node]`.

This means both variables point to the same list. Since lists are mutable, when you append the neighbor node to its path, both `paths[node]` and `paths[current]` are modified because they are the same list. This results in wrong paths, although the distances are correct.

Fix that bug by assigning a copy of `paths[current]` to the neighbor node path. Modify the existing assignment inside your `if` block.

# --hints--

You should use the slice syntax to assign a copy of `paths[current]` to the neighbor node path.

```js
({ test: () => assert.match(code, /^(\s*)if\s+paths\s*\[\s*node\s*\]\s+and\s+paths\s*\[\s*node\s*\]\s*\[\s*-\s*1\s*\]\s*==\s*node\s*:\s*^\1\s{4}paths\s*\[\s*node\s*\]\s*=\s*paths\s*\[\s*current\s*\]\s*\[\s*::?\s*\]/ms) })
```

# --seed--

## --seed-contents--

```py
my_graph = {
    'A': [('B', 3), ('D', 1)],
    'B': [('A', 3), ('C', 4)],
    'C': [('B', 4), ('D', 7)],
    'D': [('A', 1), ('C', 7)]
}

def shortest_path(graph, start):
    unvisited = list(graph)
    distances = {node: 0 if node == start else float('inf') for node in graph}
    paths = {node: [] for node in graph}
    paths[start].append(start)

    while unvisited:
        current = min(unvisited, key=distances.get)
        for node, distance in graph[current]:
            if distance + distances[current] < distances[node]:
                distances[node] = distance + distances[current]
--fcc-editable-region--                
                if paths[node] and paths[node][-1] == node:
                    paths[node] = paths[current]
--fcc-editable-region--                    
                else:
                    paths[node].extend(paths[current])
                paths[node].append(node)
        unvisited.remove(current)

    print(f'Unvisited: {unvisited}\nDistances: {distances}\nPaths: {paths}')

shortest_path(my_graph, 'A')

```
